Undo / Redo done

Done with undo and redo, got the history list up and running to but I have to work some more on that one. And make some proper graphics for it to. And well the only actions really implemented is EntityAdded and EntityRemoved, but gonna make the layer added removed actions when I get to write the code that actually adds and removes layers [smile].

So now I have to come up with what to write next, I think its gonna be the layer form, won't be to hard either, should have it functional the next time I get to code some.

After that there isn't that much more to do, just the polishing, but no major parts. No major parts that I have already decided, but I hope to come up with some more soon. I'll look at some other free leveleditors and perhaps get some inspiration, some suggestions on what to add would also be appreciated.